It has been disclosed that isobutene oligomers or polymers with a terminal double bond or terminal chlorine can be prepared by cationic polymerization. In particular, the end groups have structure A EQU --CH.sub.2 --C(CH.sub.3).sub.2 --CH.sub.2 --C(CH.sub.3).sub.2 Cl (A)
Oligomers or polymers of this type can be prepared, for example, by use of the Inifer technique as disclosed in U.S. Pat. No. 4,276,394 with suitable mono- or oligofunctional initiators. This results directly in compounds which do indeed contain chlorine bonded to tertiary carbon as end groups, but the suitability of this for subsequent reactions is low.
Preferred starting materials for subsequent reactions are, by contrast, the adducts of HCl with oligomers or polymers which in turn are prepared by cationic polymerization of isobutene or olefinic C.sub.4 cuts. These starting compounds can be obtained, for example using catalysts such as BF.sub.3, as described in DE-A 2,904,314. It has also been disclosed that isobutene can undergo cationic oligomerization to give olefins of the structure B or C EQU --CH.sub.2 --C(CH.sub.3).sub.2 --CH.sub.2 --C(.dbd.CH.sub.2)--CH.sub.3 (B)
or EQU --CH.sub.2 --C(CH.sub.3).sub.2 --CH.dbd.C(CH.sub.3).sub.2 (C).
The latter can be converted, in accordance with a not previously published proposal, with HCl into suitable chlorine-containing products. These processes or reactions result initially in compounds which have terminal chlorine bonded to tertiary carbon atoms but whose suitability as such for subsequent reactions is, as mentioned, low. In particular, it is not possible to convert the chlorine substituents into, for example, primary hydroxyl, amino, --CH.dbd.CH.sub.2 or carboxyl, because HCl is very easily eliminated both in alkaline and in acid media to result in a double bond which has low reactivity and migrates into the interior of the chain, especially in acid medium.